Electronic packaging structures of the type described above are known in the art including, for example, those shown and described in U.S. Pat. Nos. 4,849,856 (Funari et al), 4,914,551 (Anschel et al), 4,962,416 (Jones et al) and 4,965,700 (McBride). See also U.S. Pat. Nos. 5,057,969 (Ameen et al), 5,115,964 (Ameen et al), 5,133,495 (Angulas et al) and 5,203,075 (Angulas et al) for related structures. Such packaging structures, as defined in these patents, typically utilize at least one thin film, flexible circuitized substrate as part thereof. Typically, such circuitized substrates include a thin dielectric (e.g., polyimide) layer having at least one circuit layer (e.g., chrome-copper-chrome) thereon. Such thin film, flexible circuitized substrates may be positioned on and electrically coupled to another circuitized substrate (e.g., printed circuit board) to thereby electrically couple a semiconductor device (chip), which is connected to respective portions of the thin film, circuitized substrate's circuitry, to corresponding circuitry on the additional substrate. The aforementioned U.S. Pat. Nos. 4,849,856, 4914,551, 4,962,416 and 5,057,969 illustrate representative examples of such packaging structures which utilize this means of connection.
Thin film, flexible circuitized substrates as produced today possess several distinct advantages (e.g., high density, flexibility, relative ease of manufacture, etc.) desired in the information handling systems field.
As understood from the following, the invention is able to readily utilize such flexible circuitized substrates in combination with precision soldering techniques to produce a resulting electronic package structure of relatively high density. Such soldering techniques have been developed and utilized with much success by the assignee of the present invention to thereby provide resulting products at relatively low cost. Examples of such precision solder processes are defined in detail in the aforementioned U.S. Pat. Nos. 5,133,495 and 5,203,075. Both of these patents are thus incorporated herein by reference, as are the others cited above.
As defined in U.S. Pat. Nos. 5,133,495 and 5,203,075, minute solder elements (e.g., balls) are precisely positioned at locations on circuitized substrates to interconnect these substrates in a sound and effective manner.
As understood from the following, the invention is able to combine the above and similar soldering techniques with the utilization of flexible circuitized substrates to the extent that, uniquely, such solder elements can be precisely positioned immediately beneath the semiconductor device (chip) which forms part of the final package structure, while also providing effective means for electrically coupling conductive elements which form part of the flexible substrate to this device. The invention combines these advantageous teachings with a conventional, somewhat harsher procedure (thermal compression bonding) to thus also benefit from the known advantages of said procedure (e.g., reduced cost).
It is believed that an electronic packaging structure possessing the above advantageous features and others readily discernible from the teachings herein, and a method for making same, would constitute significant advancements in the art.